1. Field of the Invention
The present invention relates to a method and apparatus for manufacturing a light emitting diode (LED) device, and more particularly, to a method and apparatus for manufacturing an LED device, whereby a fluorescent solution prepared by mixing a fluorescent material with a liquid synthetic resin is dispensed onto an LED chip.
2. Description of the Related Art
Light emitting diodes (LEDs) are generally manufactured as LED devices by cutting a plurality of LED chips manufactured on a wafer and by mounting the plurality of LED chip on a package. The LED chip each emits blue or red light. When each LED chip is coated with a fluorescent solution including a fluorescent material, color of light generated from an LED device is changed according to the amount of fluorescent material coated. LED devices that emit white light or other color lights may be manufactured by dispensing an appropriate amount of fluorescent solution onto the package on which the LED chips are mounted.
After each LED chip is coated with the fluorescent solution, power is applied to the LED device so that the LED device emits light, and light characteristics of the LED device are tested using a spectroscope. Generally, color coordinates of light emitted from the LED device are measured. The light characteristics of the LED device are represented by values on color coordinates of 1931 international commission on illumination (CIE). Color coordinate values of light generated from the LED chip are changed by the amount of fluorescent material coated. The color coordinate values of the LED device are significant specification of the LED device. When the color coordinate values of the LED device exceed a predetermined range, the LED device is determined as a defective good.
A dispenser for dispensing the fluorescent solution adjusts the amount of fluorescent solution dispensed onto each LED chip, thereby adjusting the color coordinate values of the LED device. In order to adjust the color coordinate values of the LED device by adjusting the amount of fluorescent solution, a dispenser that adjusts the amount of fluorescent solution in a very small unit is required.
Some general dispenser performs test dispensing, measures the weight of a dispensed resin to calculate a dispensing amount (flow rate) for each unit time and then adjusts the dispensing amount by using the calculated dispensing amount (flow rate). However, the minimum unit of weight that may be measured by a scale with a proper price is about 1 to 10 g. Since the minimum unit of weight that may be measured by using a scale is limited, there is a limitation in finely adjusting the amount of fluorescent solution by using general methods.
The fluorescent solution used in a process of manufacturing an LED device is hardened as time elapses, and viscosity of the fluorescent is changed. Viscosity of the fluorescent solution is also changed according to temperature. Since viscosity of the fluorescent solution is changed non-linearly with respect to a factor, such as temperature, or the like, it is very difficult to apply viscosity of the fluorescent solution calculated by a numerical value to the dispenser. The content of the fluorescent material mixed in the fluorescent solution may be changed slightly every time. A dispensing environment is continuously changed due to mechanical characteristics or an unmeasurable factor of the dispenser. General dispensers cannot meet with such a change. In particular, characteristics of the LED chip supplied to a process of dispensing the fluorescent solution are not constant due to a condition of the previous process in which the LED chip is manufactured. Thus, an apparatus and method of manufacturing an LED device that may adjust light characteristics of the LED device in consideration of the circumstances is required.